This invention relates to a continuous-cycle electroplating plant.
Electroplating plants, e.g. for small metal items, which include one or more lines of tanks designed to contain treatment liquids (such as solvents, dissolved acids, degreasing agents, neutralizing agents, and the like) and transversely arranged one after another between two slide guides, are known in the art. An overhead crane structure is usually mounted movable along the slide, guides to shift, immerse, lift and rotate in succession plurality of transportable tumblers (usually consisting of a plastics material, such as propylene) into and out of the tanks in accordance with a desired sequence of operation steps. A complete electroplating cycle requires one or more tanks specifically designed to be used for one of the following wet preparation or cleaning steps of the metal material to be treated, namely pre-degreasing, pickling, degreasing, and neutralizing, and one or more specific tanks for electroplating proper as well as one or more tank for passivating or coloring the electroplated material.
Although quite satisfactory in various respects, such plants have a number of disadvantages which adversely affect their productivity and efficiency. Thus, for example, prior plants cannot be operated on a continuous basis, as the various tumblers must dwell for specific time intervals in the various tanks, which results in a large amount of time being wasted for transferring the various tumblers from one tank to the other and in the need of using complex and costly apparatuses for handling and monitoring each tumbler. Moreover, prior plants require large amounts of treatment liquids in the tanks. Such liquids require frequent purification through suitable apparatus. Large amounts of liquid in the electroplating tanks affect migration and deposition rate of the plating metal ions as the latter have to follow long paths before reaching the material to be planted. In addition electroplating plants cannot be fully automated at acceptable costs, and thus they must be installed indoors to protect operators against inclement weather, which requires, in turn, availability of special arrangements and depuration systems to prevent environmental pollution.